I can tell you that about my pictures:
Look on your computer and decide, which pictures you want to take; if they are bigger than (I think) 300 mb you have to shrink them.
Go to the forum, click on reply to a message and you get the "reply window". At the bottom there is "Attach files", click on it and you get another window; on the top of this one is the upload function for the pictures.
You can upload several photos and after that you will always get the listing of the pictures when you click on "Attach file" and take the one you want.
Hope that helps.
Uli,45, Germany